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EEALLE-NEER. TELEPHONE EXCHANGE SYSTEM. No. 511,875. Patented Jan. 2,1894.-

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R.GALLENDER. TELEPHONE EXCHANGE SYSTEM.

No. 511,875. Patented Jan. 2, 1894,.

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No. 511,875. Patented Jan. 2, 1894.

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R. O ALLENDER. TELEPHONE EXCHANGE SYSTEM-.1

N0. 511,875. Patgnted Jan. 2, 1894.

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(No Model.) R. GALLENDER.

TELEPHONE EXGHA'NGE SYSTEM.

No. 511,875. Patented Jan. 2, 1894. I

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UNiTnn STATES 'Arnrtr rrrone ROMAINE CALLENDER, OF BRANTFORD, CANADA.

TELEPHONE-EXCHANGE SYSTEM.

SPECIFICATION forming part of Letters Patent No. 511,875, dated January2, 1894.

Application filed August 13,1892.

To all whom it may concern.-

Be it known that I, RoMAINE CALLENDER, a subject of the Queen of GreatBritain, residing at Brantford, Ontario, in the Dominion of Canada,haveinvented certain new and useful Improvements in TelephoneExchan e'Systems, of which the following is a specification.

My invention is directed particularly to improvements in that type ofapparatus known in the art as automatic telephone exchange systems inwhich the subscribers, through the agency of apparatus located atoutlying stations and additional apparatus located at a central or mainexchange, are enabled to antomatically efiect intercommunication witheach other in any desired order.

My invention has for its objects, first, the construction of such anautomatic telephone exchange system as will enable any subscriber toinstantaneously effect automatically intercommunication through acentral exchange office with any other subscriber and at the same timeprevent the possibility of any disturbance or interruption from a thirdsubscriber until after the first two have held their conversation orbeen rung ofif second, to provide means whereby a preliminary signal isfirst sent in to the central station, all of the lines disconnected froma common switching device and finally to connect the lines desiredautomatically; third, to provide means whereby any two lines of anindefinite number may be automatically connected on sending a simplemake and break signal from any outlying station to the central station;fourth, to provide means whereby the subscriber signaling may make theconnection desired from his own office through the central office overhis own line by simply turning in a signal from a transmitter located inor near his own telephone box; fifth, to provide means whereby when asignal is turned in, a constantly operating generator located in thecentral station may be automatically connected in circuit with the lineof the subscriber sending the signal and that of the subscriber signaledand the call bells at both stations rung, thereby indicating that thetwo lines are in circuit; sixth, to provide mechanism which shall enableany subscriber to connect his line with that of any other subscriberautomatically; to signal the subscriber want- $erial No. 442,948. (Nomodel.)

ed and finally after the conversation hasbeen effected to automaticallyring oif both subscribers and restore the lines to their normalcondition; seventh, to provide mechanism in the nature of automaticapparatus whereby any two or more subscribers having telephoneinstruments located on any two of an indefinite series of outlyingtelephone lines connected withswitching mechanism at a centralstationmay effect any of the results necessarily attributable to theapparatus hereinafter described, the novel features of which areparticularly pointed out in the claims at the end of this specification.I accomplish these several objects with the apparatus hereinafterdescribed, for a full and clear understanding of which reference is hadto the accompanying drawings in which- Figures 1, 2, 3, 4, 5,6,7 and 8are diagrammatic views illustrating the entire system and for a clearunderstanding of which, the first eight of the sheets of the drawingsshould be laid side by side in sequence. Fig. 9 is a part diagrammaticpart plan view of that portion of the apparatus which I shall term theisolator. Fig. 10 is a detail end elevational view of the circuitcontrolling apparatus which regulates the releasing mechanism of theseveral portions of the clock or time controlled apparatus. Fig. 11 is aplan view of the general switching mechanism whereby all of the lineswhich enter the exchange are antomatically interrupted when apreliminary signal is sent in from a subscriber and remain interruptedduring the time that the anto matic connection is being effected betweenthe subscriber who signals and the subscriber signaled. Figs. 12 and 13represent diagram m'atically a complete system of nineteen lines showingthe circuit connections from nineteen outlying stations to and throughthe automatic central station with so much of the controlling apparatusas directly influences the switching portions of the mechanism, and alsoillustrating in the latter figure the radiating system of connectingconductors for connecting up additional lines. Fig. 14 is a diagrammaticview illustrating the circuit connections in the central station for asystem of nine-hundred and ninety-nine lines, the operating apparatusnot being shown.

Before entering upon a detailed description of the drawings in orderthat a general understanding may be had of my novel automatic system, itmay be well at the outset to indicate that all of the automaticapparatus in the nature of switching apparatus, time controlledmechanism and the magneto call generator are located at the central ormain office into which the subscribers lines all enter, there being oneor more sets of subscribers instruments located on'each independentline, each of which sets of instruments is provided with acircuitbreaking transmitter like that shown in Fig. 1 and lettered T,there being also a signaling battery B A for each independent lineearthed at E. All of the apparatus therefore shown in Figs. 2 to 11inclusive is located at the central station and all of the incomingindependent wires on which the subscribers instruments are located runto a rotary or oscillating general circuit breaking cylinder 0 Figs. 5,11, and 13, their electrical continuity being maintained through aseries of metallic contact plates or strips 6 on the upper surface ofthis cylinder.

In order to simplify the illustration, I have shown a single outlyingline numbered 1, Fig.

, 1, earthed at E and provided with the usual lightning arrester L,Blake transmitter T transmitting battery B A, receiving magnetotelephone T hung upon its hook in the ordinary way, all of the circuitconnections thereof for the transmitter T and receiver T being what isnow well understood by those skilled in the art; the right hand side ofthe lightning arrester L being connected by the subscribers line 1 toand through the upper portions of Figs. 2, 3 and 4 to the generalcircuit breaker C (Figs. 5, 11 and 13) through the contact springs 3metallic plates a to No. 1 of a series of contact plates numbered from Oto 9 which in turn are connected through corresponding subscribers wiresand similar apparatus located at like outlying stations.

In the telephone box of each subscriber or at some point easilyaccessible to the subscriber, is located a rotary transmitter Tconsisting of an insulating cylinder having a series of ten metallicstrips or successively of different length located upon its surface andelectrically in contact with the metallic axis of the cylinder which inturn is connected through a contact spring y with a signaling battery BA earthed at E. The number of these metallic plates at is equal to thatof a corresponding set of conductingsprings a the free ends of which areadapted to bear upon the cylinder T and make contactin succession withthe plates a, While their other ends are secured to a fixed set ofelectrical conducting plates numbered 0, 1, 2, 3, &c., to 9, inclu sive,said contact plates being lettered 0 and corresponding in number withthe number of subscribers lines under the control of the first portionof the apparatus at the central station which I denominate as numericalreoeiver No. 1. See Figs. 5 and 13.

S w is a rotating conducting switch the free end of which is adapted tocontact with the ends of the conducting plates 0 and M B is a magnetocall bell electrically connected on one side to the lightning arrester Lwith the earth E and on the other through a pair of conducting springs25 with a short conducting plate z' carried by the cylinder T and inturn through the telephone hook with the subscribers line 1 as clearlyshown.

The rotary transmitterT with the transmitting batteryB A and the circuitconnections just described constitute the only apparatus used by me atthe subscribers stations for efiecting automatic intercommunicationthrough a central station with outlying subscribers on independentlines.

I shall now describe in general terms the apparatus located at thecentral station, after which I shall describe the mode of operation ofthe entire system.

In Fig. 6 is shown at the bottom of the drawing, a battery B A and aseries of circuits numbered 12, 7, 14, 17, 22 and 24 running to step bystep mechanism illustrated in Figs. 2, 3, 4, 5, 7, 8 and 13. Theseseveral circuits are automatically opened and closed at the points q gby one or more conducting extensions m of a pendulum R carried by aclock beating seconds or any other preferred elements of time, P beingthe pendulum ball. I have shown this method of closing these severalcircuits by a single conducting extension m and through the agency of apendulum for the reason that this is the simplest method of illustratingthis portion of the apparatus. It will be understood that it would ofcourse be preferable to provide independent circuit closing contacts q qfor each circuit 12, 7, 14, 17, 22 and 24 and that the circuits might beclosed with sliding contacts carried by a rotary drum adapted to makeone revolution in any desired time or that there might be a separaterotary drum for each set of contacts and each controlled by anindependent clock mechanism and adapted to rotate each at such a speedas the necessities of the case might demand.

Referring now to Figs. 2, 3, 4, 7 and the lower part of 8, that portionof the apparatus which discloses ratchet wheels or ratchet sectors withholding and propelling pawls and operating electro-magnets together withreleasing devices are all controlled directly in their forward actionstep by step by the clock mechanism shown in Fig. 6.

That portion of the apparatus at the bottom of Fig. 2 lettered E I termthe general time limit apparatus, its object being to operate for aspecified length of time under the control of the clock (Fig. 6) duringwhich time the subscriber shall have had an opportunity to complete hissignal and make the circuit connection with thesubscribersought, afterwhich this portion of the apparatus is automatically released andconversation proceeded with as will be fully described later on.

ft I O0 That portion of the apparatus illustrated in Fig. 3 by theletter O I denominate as the magneto signaling controlling instrument,its function being to automatically connect the constantly drivenmagneto signaling generator H in a looped circuit between any twosubscribers lines after they have been automatically connected togetherthrough the central station.

That portion of the apparatus represented at the bottom of Fig. 4 andlettered C I denominate as the numerical separator, its function beingto enable any subscriber to select a certain one of the remainingsubscribers lines where the total number of those lines amounts to morethan nine: that is tosay, by the use of the switch S10 and thetransmitter T for one revolution of said transmitter the subscriber mayconnect his line with the desired one of the lines 0 to 9 in Fig. 5, butwhen the outlying subscribers lines amount to more than nine it will benecessary to make two or more revolutions of the transmitter T and tocorrespondingly change the location of the switch S w to any one of thedesired numerals O, and 1 to 9 inclusive, between which revolut-ions ofthe transmitter this and other like numerical separators act to aid inbringing about the desired connection as will be fully described inconnection with the description of the mode of operation. To make thisstatement last made more clear, it is to be understood that for thefirst system of outlying subscribers wires illustrated in Fig. 5, theswitch handle S w is to be placed upon that one of the conducting strips0 O to 9 inclusive corresponding to the subscribers wire wanted and onerevolution given to the transmitter T by the handle H and that forconnections between the subscriber and any higher number of outlyingsubscribers circuits, such as is shown in Fig. 8, the switch handle S 20would be placed upon any one of the conducting strips 0 to 9corresponding to the subscribers wire wanted in the higher number thannine and the transmitter T given a second rotation. In the meantime thenumerical separator illustrated at the bottom of Fig. 4 will select thecircuits of the higher order of numerals from those of the lower orderof numerals during the interval of time between the two rotations of thetransmitter T as will be fully described in the description of the modeof operation.

That portion of the apparatus illustrated in the upper portion of Fig.5, I denominate as numerical receiver No. 1. It consists of a ratchetwheel W' and conducting arm D, operating electro-magnet R and releasingelectro-magnet d, propelling pawl 72., holding pawl k releasing cord 0passing under pulley b and releasing armature lever Z V being a weightattached to a cord passing over a pulley n and secured to the shaft ofthe wheel WV,the function of the conducting arm D being to convey thecurrent from the subscribers wire to the desired outlying subscriberwhose wire is connected with one of the conducting plates 0 to 9inclusive. This numerical receiver is positively propelled by the actionof the electro-magnet R and pawl b through current impulses sent overthe signaling subscribers line by the transmitter T when rotated, asalready described.

That portion of the apparatus illustrated at the bottom of Fig. 5, Idenominate as the general circuit breaking instrument, the same beingillustrated in plan view in Figs. 11 and 13, and controlled byelectro-magnets d and d armature levers Z Z propelling pawl h andreleasing pawl k releasing cord a passing under the pulley b Thatportion of the apparatus illustrated in the upper portion of Fig. 7 andlettered G I denominate as the adjustable automatic conversationtime-limit mechanism, its function being to regulate the time for whichthe conversation between the subscribers may be held, and it iscontrolled by electro-magnets (1 d, and (7/ with propelling pawl hreleasing pawl releasing cord 0 passing under pulley Z)".

That portion of the apparatus shown at the bottom of Fig.7 and lettered(3 ,1 denominate as the automatic release controller which releases allof the apparatus not already released when the adjustable automaticconversation time-limit restores all of the apparatusat the centralstation to normal condition ready for the next signal.

That portion of the apparatus shown near the top of Fig. 8, I denominatenumerical receiver No. 2, it being a mere extension of the like portionof the apparatus shown in Figs. 5 and 13 and denominated numericalreceiver No. 1 each one of the several subscribers lines numbered from 1to 9 inclusive, Figs. 5 and 13, being connected to an instrument likenumerical receiverNo. 1. In other words each subscribers line runningout from numerical receiver No. 1 in Fig. 5 would be connected to acorresponding conducting arm D on a second numerical receiver adapted tobe connected with any one of a secondary set of subscribers, like thatshown in Figs. 8 and 13 thereby largely increasing the connectingcapacity of the system.

A more clear understanding may be had of the arrangement of thenumerical receivers or switching apparatus which connect up the variouslines with each other, on examination of Fig. 14:, where the firstnumerical receiver or numerical receiver No. 1 is shown at the bottom ofthe drawing, and through which all incoming signals pass for all linesof the entire system. The second series of numerical receivers, each ofwhich is always denominated as numerical receiver No. 2, wheneverreferred to in this specification, is seen immediately above numericalreceiver No. 1; and the third series of numerical receivers, each ofwhich is always denominated as numerical receiver No. 3, wheneverreferred to in this specification, is located above the second seriesand all signals of the third order of decimals pass these receivers, aswill be more clearly understood in connection with the description ofthe mode of operation. This figure of the drawings just referred toshows the circuit connections only for the entire system of lines andthe numerical receivers for. connecting them together in pairs in anydesired order, it being understood that auy incoming signal from anyoutlying subscriber is conveyed first to numeri cal receiver No. 1,thence through that one of the second series of numerical receiversdenominated as numerical receiver No. 2 which is called, and thencethrough that one of the third series of numerical receivers which iscalled, it being understood that all lines from 1 to 9 inclusive may becalled through numerical receiver No. 1 only while all lines from 1 to99 inclusive are connected with each other only through numericalreceiver No.1 and the necessary one of the second series connected tothe line wanted. In

other words all incoming signals of any nature whatever must passthrough numerical receiver No. 1. All incoming signals of the secondorder of decimals or from 1 to 99 inclusive must pass through numericalreceiver No. l and one of the second series of numerical receivers. Allsignals from 1 to 999 inclusive must pass through numerical receiver No.1, some one of the second series of numerical receivers and some one ofthe third series of numerical receivers.

That portion shown at the bottom of Fig. 8 of the drawings isa'd'uplicate numerical separator and is identical with that shown at thebottom of Fig. 4 of the drawings lettered Referring now to Fig. 2; L Lare switches controlled by magnets M M ing magnet for releasing theweighted switch lever 1 there being one of these releasing magnets foreach subscribers line and all operatively connected with the circuit 8with the releasing mechanism controlled by the adjustable automaticconversation time-limit apparatus illustrated in Fig. 7.

S, S and S", Fig. 4, are releasing magnets operated either by thetransmitter T or by the apparatus connected to the adj ustable automaticconversation time limit.

S and S S, Fig.4, are switches controlled by electro-magnets M M M andM.

S and S S Fig. 8, are substantial duplicates of the switches S and S Sshown in Fig.4.

K, K, K, K, K, Figs. 3, 4, 5, 7, and 8 are ratchet segments adjustablysecured to the rotary parts 0, C O O and 0 (see Fig. 8,) the size andnumber of the ratchet teeth being made dependent upon the proportionatetimes in which it is desired to rotate the disks or cylinders to whichthey are attached.

W W W WV? are weights carried by levers pivoted to the frame of theapparatus,

their inner or free ends bearing under or be-' neath the curved portionsof the sectors K so that as the disks are rotated the weights V d is areleasare lifted and when said disks are released, these weights actingthrough the levers will cause the disks and sectors to assume theirnormal positions. In place of these weighted levers I may use weightsand cords passing over pulleys like those shown at W and n in connectionwith the ratchet wheel of the general time limit apparatus in Fig. 2.

Referring now toFig. which is an enlarged view illustrating differentpositions of the circuit cont-rollers carried by the rotary disks orcylinders C, 0 C and 0 t is a strip of conducting metal secured at oneend to one of the conductors running to a releasing electro-magn et, inthis instance shown as the conductor 11, running to the releasing magnetd Fig. 2, and t is a corresponding conducting plate secured to the edgeof the disk 0', this plate being in turn connected to'the other end ofthe conductor 11. t is an elastic or yielding metallic plate carriedalso by the disk 0 but insulated from it and the plate The upper orstraight edge of this yielding metallic plate t lies snugly against theend of the disk 0', and the lower or V shaped edge is curved outwardfrom the end of said disk and so'thatit is out of electrical contactwith the fixedinnerplatef,thearraugement beingsuch that as the disk 0rotates in the direction of the arrowin the first position the free endofthe metallic plate 6 rides up over the outwardly curved end of theplate 1 so that there will be no metallic contact between the contactingplate t and the fixed plate 25 carried by the disk 0 until it leaves theupper curved or angular surface of the insulated plate 2' and assumesthe position shown in the central figure, while on rotating the disk 0'in the reverse direction as shown in the right hand of thefigure, theplates 25 and 25 will be in metallic contact as the former passes underthe insulated plate 2' and maintains contact between the plates and tuntil the disk assu mes its original position and passes out from underthe end of the yielding plate 71 as said disk rotatesin the direction ofthe arrow shown in the right hand portion of Fig. 10. The action ofthese corresponding parts in Figs. 8, 4, 7and8 in connection with thedisks 0', O O 0 and (J is the same and the releasing electro-magnets d(1 d, d, and 61 are adapted to release said disks at the properintervals of time.

I will now describe the mode of operation of the entire apparatus givingfirst a description of the method of connecting up two subscribers wherethe number of the subscribers wires so connected lies between one andnine, and then describe the method of connecting up two subscriberswhere the number of Wires is over nine, thus illustrating in the secondinstance how, with a limited number of wires connected to each numericalreceiver or two or more sets of such receivers, I may make connectionsbetween a large number of outlying subscribers wires. Suppose in thefirstin- IIO stance itis desired to connect the subscriber on v wireNo.1 and whose signaling and telephone instruments are shown in Fig. 1with another subscriber whose instruments are located on say wire No. 9.The several parts of the apparatus at the outset are in the positionshown in the drawings of Figsl toS inclusive and in full lines in Figs.12 and 13. The operator on wire No. 1 turns the switch S to into contactwith that contact plate 0 numbered O and then rotates the transmitter Tthrough the agency of handle H one complete revolution, thereby sendingto line in the direct-ion of the tailless arrows a single impulse frombattery B Aby wire 1, switch leverZ (Fig. 2) wire 2, weighted switchlever Z wire 2, relay R, wire 2, relay R, earth E thus actuating thesetwo relays Band B. The relay B being energized causes its armature toclose the circuit of battery B through the circuit 4t4: and magnet 61(Fig. 5) thereby causing the armature lever Z and propelling pawl 71 toact upon the ratchet sector K and rotate the general circuit breaker C afractional part of a revolution interrupting the circuits of all linesin the group, thus disconnecting all of the local branch lines in thecentral station connecting the numerical receiver between the metallicstrips 6 and the series of contact springs s more clearly shown in Figs.11 and 13. At the same instant the relay R which was energized asalready described, causes the armature lever r to be drawn down so thatthe hook lever 7L2 near its right hand end catches the free end of theweighted switch lever Z The cord 0 attached to the other end of thearmature lever r and to a detent hook his simultaneously drawn down overthe pulley 1), thereby drawing the hook h out of the path of a catch onthe face of theisolator cylinder I, there being a separate relay R andcorresponding circuit and mechanical connections for each of theincoming subscribers lines 1 to 9 inclusive as shown in Figs. 9 and 12,the arrangement being such that the operator signaling will draw hisparticular detent hook it out of the path of its catch, while theremaining detent hooks h will remain in the paths of their catches. Atthe same instant that the armature r is drawn down by the relay R alocal circuit 3 will be closed from the battery B to the localelectro-magnet d imparting to its armature Z and a detent hook haforward motion,thereby rotating the isolator cylinder I a fractionalpart of a revolution and allowing a detent pawl 13 to fall behind a stopon a disk attached to the shaft of the isolator cylinder. This forwardmotion of the isolator cylinder causes all of the switch levers Z (seeFigs. 2 and 9) to be tilted forward under the influence of their hooksit except that one which has just been described as having beendisconnected from the isolator cylinder by the cord 0. It

will thus be seen that the circuit isinterrupted between all of theincoming subscribers wires at the switch Z and the contact points a bythis action of all of the switch levers Z except the one last referredto, so that no circuit can now be closed for incoming signals from otheroutlying subscribers instrum ents.

It is to be noted also that the clock or other time mechanismillustrated in Fig. 6 is supposed to be running continuously, thusconstantly making and breaking the circuit of the battery B A betweenthe yielding contact springs q q and through the circuits 12, 7, M, 17,22 and 2t and apparatus connected therewith when any of said circuitsare closed at other points as will be described later on. Thepreliminary impulse sent in by the transmitter T through contact plate 0switch S w and circuit No. 1 as just described, has thus disconnectedall of the outlying subscribers lines, save the one who has justsignaled. As soon therefore as the relay E (Fig. was demagnetized, itsarmature r and hook lever 72/ shifted the circuit from the lower contactpoint a; at its left hand end to a second contact point 00' j ust above,and a new No. 1 circuit was established by wire l,left hand switchL,wire I, right hand magnet M of the right hand switch L thence by wire1 through back contact stop of the armature lever of relay R and finallythrough relay R to earth at E both of said relays being found in Fig. 3of the drawings. The electro-magnets R R 850., which control themovements of the numerical receivers and the switching magnets S S&c.,Fig. 8, which control the circuits in connection therewith, shouldbe somewhat more sluggish than the relays R and B, Fig. 2, in order thatthe preliminary impulse sent in from any outlying station may not affectsuch of those magnets as may be in circuit before the branch circuitsare all interrupted at the general circuit breaker; or the same may beeffected by utilizing a signaling battery B A, Fig. 1, at eachsubscribers station of considerablyless electro-motive force than thebattery B A, Fig. 3, which controls the aforesaid electromagnets. Theoperator at station 1 now places the switch S w in contact with plateNo. 9. Supposing he desires to connect his wire with some subscriber onwire No. 9. He then gives to the transmitter '1 one complete revolutionas before, thus sending ten impulses over the line in the same directionas before through lever 7?,(Fig. 2,) upper contact 03, wire 1, left handswitch L, wire 1, right hand portion of magnet M which controls andturns the switch L thence through relay R to earth at E at the bottom ofFig. 3 as already described. These ten impulses therefore actuate therelay R and cause the battery B A at the bottom of Fig. 3 to send tensuccessive impulses forward from earth E by armature of relay R andfront contact stop by wire 1 through the left hand switch S, (Fig. 4,)thence through wire 16 and right hand magnet M which controls the twopoint switch S S, (Fig. 4,) thence by wire 16 through electro-magnet Rto earth at E These ten impulses therefore impart to the numericalreceiver No. 1 in Fig. 5, ten forward steps through the agency of thehook h and retaining pawl k thereby placing the conducting arm D ofthis'receiver ultimately in contact with the right hand plate 9 asclearly illustrated in dotted lines in Fig. 13 and hence withithecircuit running to the subscriber desire Returning now to the right handswitch L at the top of Fig. 2, it will be seen that by the act ofshifting the lower end of its switch arm to the lefta clock circuit isestablished from the battery B A (Fig. 6) by way of the conductors 7-7which circuit includes the actuating electro-magnet d at the bottom ofFig. 2 so that as the pendulum vibrates the generaltime-limit apparatusEissetin motion through the operation of the armature lever Z andpropelling pawl h This mechanism continues to advance step by stem for aperiod of say twenty seconds or twenty beats of the clock pendulum andduring the first fifteen seconds of this forward motion, the contactplate e of the general-time-limit apparatus is brought under the twoconducting springs s 8, while the holding pawl retains the apparatus asit is advanced step by step and the restoring weight and cord W aredrawn up over the pulley n. When the contact plate (2 passes beneath theconducting springs s a new clock circuit 12 is established through thecontact points q q and battery B A said circuit 12 including anactuating electro-magnet d for the magneto signaling controllinginstrument represented by the letter C (Fig. 3) so that the ratchetsector K through the agency of the propelling pawl h, armature lever Zand retaining hook 7c is caused to advance step by step as the clockcloses the circuit at q q in Fig. 6. During the first of the forwardsteps of the tooth sector K and hence of the magnetosignaling-controlling apparatus 0, the conducting plate e carriedthereby is brought under the two conducting springs s s and anadditional circuit is thereby closed through the conductor l3l3 from thebattery B which circuit includes a releasing magnet d for the generalcircuit-breaker shown at the bottom of Fig. 5, thereby performing twofunctions at the same time: namely,first releasing the generalcircuit-breaking cylinder 0 through the agency of the armature lever Zreleasing cord 0 propelling pawl 7L6 and detent pawl I0 and allowingthis cylinder to assume its normal position or that now shown in Figs.5, 11 and 13, thereby again restoring all of the subscribers, circuitsinto through connection with the contact plates a and the numericalreceiver circuits, as clearly shown in Figs. 5, 12 and 13. It will benoted at this time that although the general circuit has beenre-established for all of the local branchcircuitsatthegeneralcircuit-breakerasshown in Figs. 5, 11 and 13, all ofthe subscribers circuits except the signaling circuit are now broken attheir points of juncture with the switch levers Z by virtue of theprevious rotation of the isolator cylinder I so that there is only onepath for an incoming current.

The circuit 13 which includes the battery B contact springs 8's and thereleasing magnet 03 includes also a relay R located near the bottom ofFig. 3, and it is therefore apparent that during the time that theconducting plate (2 of the magneto signaling controlling instrument 0remains under the contact springs s s the armature of relay R will beheld forward on its front contact stop. The result therefore is that theconstantly operating magneto generator H is now looped in circuit withboth of the incoming subscribers lines 1 and 9, and the magneto bells MB at both stations continue to ring during the time that the contactplate e is under the springs s's. As the instrument 0' continues torotate circuit is made through conductor 9 and contact springs 25 and tand the battery circuit B near the center of Fig. 3 is closed throughcircuit 9 including the releasing" magnet d", (Fig. 5,) the right handmagnet of the left hand switch L at the top of Fig. 2 and the left handswitch magnet M of the switch which controls the adjustable-conversation-time-limit apparatus in Fig. 7. Consequently theleft hand switch L at the top of Fig. 2 is turned with its lower pointin contact with the left hand contact point as shown in dotted lines inFig. 12. The contact spring t of the magneto controller'O, Fig. 3, hasridden over the insulated plate 2' and assumed the position shown in thecentral View of Fig. 10, thereby closing the circuit of battery Bthrough wire 11 t0 the releasing magnet cl thus releasing thegeneraltime-limit apparatus E in Fig. 2, and allowing it to return tonormal position, it having first advanced far enough to close thecircuit 10 through contact springs t with a conducting plate 0 so as toenergize the left hand magnet M of the right hand switch L at the top ofthe drawings and return it to normal position thereby rupturing theclock circuit 7 7. The general time-limit apparatus for controlling thetime of turning in the signal has been returned to normal position andhas shifted the switch of the right hand switch L its at the top of Fig.2 to its normal position, the

magneto signaling controlling instrument has been returned to normalposition through the agency of the releasing magnet d and the magnetogenerator cut out of circuit. The adjustable automatic time-limitconversation apparatus has been set in motion through the agency of thecircuit 9, magnet M and switch S to (Fig. 7) a circuit having beenestablished through said switch, the conductor 2e, operating magnet dand the clock circuit at Fig. 6.

It will be noticed that the circuit 9 is provided with circuit closingdevices at two points, one on the apparatus O'in Fig. 3, and the otheron the general time-limit apparatus E in Fig. 2, the arrangement beingsuch that although electrical contact is made between theplates t and ias O advances, the circuit will notbe closed between the plate 7? andthe rotary plate carried by thegeneral time-limit apparatus until thelatter has been released and returned to normal position therebyallowing the general time-limit apparatus to be released first and toafterward release the instrument and to perform the other functionsalready described. lVhen the relay B (Fig. 3) closed the circuit frombattery B A through line 1, the left hand switchS of Fig. 4 and theright hand magnet M wire 16 and magnet B (Fig. 5) the first impulse sentover the line caused the two point switch S S to reverse its positionand to close the clock circuit 17, thereby starting the numericalseparator C almost simultaneously with the general time-limit apparatus(Fig. 2). As the numerical separator advances under the action of thearmature Z and hook lever h it brings the contact plate e under thecontact springs s 5 thereby closing a local battery circuit 15 frombattery B through the left hand magnet M of the double switch S Srestoring the switch to its normal position and also through the lefthand magnet M of the switch S shifting said switch into the reverseposition and hence directly in circuit with the arm D of the numericalreceiver in Fig. 5 so that the magneto call currents from the magnetogenerator H were caused to take the path through the conductor 1,joining the two circuits thus connected togetherduring the time that thearmature of relay R was held forward on its front contact stop, whilethe contact plate 6 of the magneto signaling controlling instrument waspassing under the springs s s. The uninterrupted talking circuittherefore between the two lines 1 and 9 is as follows. Passing from theearth at station 1 in the direction of the tailless arrows through thewire 2 (Fig. 2) lever Z, wire 2, lever Z upper contact :1." upon whichlever Z is held by hook 7L2, wire 1, switch L and left hand contactpoint upon which it is now resting, wire 6 through ringing otf magnet Sin Fig. 4, wire 6,.wire 1 directly to the numerical receiver through thearm D to the wire 9 and thence through the contact springs 5 3 metallicplate 6 on the general circuit breaker directly to the outlyingsubscriber. See also Figs. 12 and 13. As the numerical separatoradvances through its complete phase the local circuit of battery B seenat the bottom of Fig. 4 is closed through the electro-magnet d andconductors running to the contact plates 25 and t the operation beingthe same as already described in connection with like parts illustratedin Fig. 10, the releasing armature lever Z causing the hook lever 71 anddetent hook k to allow the sector K and disk 0 to return to normalposition. Just before the magneto signaling controllinginstrument wasreturned to its normal position by the releasing electro-magnet d incircuit 9 and at the instant that the general-time-limit apparatusreturned to its normal position and closed the circuit 9-9, the switch S10 of the ad ustable automatic conversation time limit apparatus (Fig.7) was turned into its upper position under the influence of magnet Mwhich is also in circuit 9 so that after the magneto signal has beensentin and the two subscribers connected together as already described,this adjustable automatic conversation timelimit apparatus is now put inoperation by the agency of the clock circuit 24 which runs to the clockand energizes the propelling electro-magnet- (1 thereby causing thesector K of this apparatus to advance step by step for a definite numberof seconds or minutes or such time as may be allowed for conversation,the apparatus shown in Fig. 7 of the drawings merely indicating theapplication of this timeliniit principle. As the two subscribersconverse therefore the apparatus C advances and ultimately the contactplate e rides under the conducting springs s 5 closing the circuit ofthe battery 13 through the conductors 18 to the releasing electro-magnetS near the center of Fig. 4 of the drawings, thereby lifting thearmature lever 21 and allowing the armature lever o to be Withdrawn fromthe notch on the under side, thus locking the armature o in its upperposition in contact with a conducting contact connected to the clockcircuit 14. On the first closure of the clock circuit therefore throughthe circuit 14 the left hand switch S of Fig. 4is shifted by magnet M toits first or normal position and simultaneously the automatic releasingmechanism at the bottom of Fig. 7 is stepped forward under the influenceof the electro-magnet (1 until the contact plate 6 is carried under thecontact springs 3 thus closing the battery circuit B through theconductor 8 and right hand electro-magnet Mflshifting theconversation-time-limit switch S 10 back to its normal positionsimultaneously energizing the releasing electro-magnet 01 in the samecircuit, thereby releasing the adjustable automatic conversationtime-limit mechanisin and allowing it to rotate back to its normalposition. At the same instant the releasing magnet d in the samecircuit, 8, of the numerical receiver in Fig. 5 is actuated, allowingthe weight .W' to return the conducting arm D of the numerical receiverto its first or normal position. The electro-magnet s of the ringing offapparatus F Fig. 4, is also caused to draw the armature 7) into itsforward position and release the armature o. The electro-magnet M of theupper left hand switch L in Fig. 2 being in the same circuit 8 causesthe switch to be turned to its first or normal position and thereleasing magnet al which is also in circuit 8 in Fig. 2 lifts the pawlp and allows the isolator cylinder to be restored to its normalposition. The releasing magnet cl which is also in circuit 8 in Fig. 2is caused to release the armature lever hook 72. from the end of theWeighted lever t thereby allowing said lever to assume its original theisolator cylinder, Fig. 2.

or normal position. Lastof all theautomatic release itself at the lowerpart'of Fig. 7ofthe drawings is effected through the agency of a localcircuit and electro magnet (Z in the same manner as the apparatus 0 atthe bottom of Fig. at was released as heretofore described. It isnowapparent that the several parts of the apparatus put in operationfrom the transmitter Tat the station ofthe signaling subscriber haveserved their various functions in sequence and that the adjustableautomatic conversation time limit apparatus having limited the time ofthe conversation, the entire mechanism at the central station has againassumed its normal condition and that the isolating cylinder I has againconnected all of the outlying subscribers lines With the signalingreceiving mechanism for said lines at the central station. Any otheroperator may now turn in his signal and automatically connect hisparticular line with any other line in'the system, the operation beingidentically the same as has heretofore been described. Should anysubscriber attempt to signal during the time that tne apparatus isin useby reason of a signal previously sent in, it is apparent that he willreceive no signal on his own magneto-bell, his line being like that ofallsubscribers, save the one who has previously signaled, out out at Hemust wait therefore until he obtains a signal on his own bell onturningin a signal before he is aware of the fact that his propercircuit connections have been made. The absence of such a return signalis indicative to him of the fact that the system is in use and that hemust wait until the proper circuit connections are again automaticallymade at the central station. It is to be understood however thatalthough all of the subscribers outlying lines, save the one who issignaling, have been cut out of circuit at the isolating cylinder (Fig.2) for transmitting signals, all of said lines are still connected withthe numerical receivers for receiving signals at the points 0 to 9inclusive over which the conducting arm D passes and also through thecontact springs s s and conducting plates a the latter attached to thegeneral circuit-breaking cylinder 0 (See Figs. 5 and 13.)

I will now describe how I am enabled to unite two or more subscribersinstruments located in independent outlying subscribers lines where thenumber of such outlying lines is greater than nine.

My system of uniting any two of an indefinite number of subscriberslines is based upon What I term the units, tens, and hundreds principle,and I connect the first nine subscribers lines running into the centralstation with a numerical receiver which is connected to ten local orbranch wires, each one of these local or branch wires being connected inturn to one of a series of secondary numerical receivers having in turnten similar connections, each one of which runs to one of a series ofthird numerical receivers and so on indefinitely. Automatlc switchingapparatus is also included in circuit between the several numericalreceivers whereby the circuit connections are shifted so that the mainbattery B A at the bottom of Fig. 3 is caused to automatically advancethe numerical receiver and its conducting arm D to the desired pointthrough the agency of the relay R (Fig. 3) and the electro-magnet R(Fig. 5) and then shift the circuit connections from this electro-magnetR to the electro-magnet of the next succeeding numerical receiver and soon in sequence, the main battery B A being utiliZed to drive thesenumerical receiversin succession. In other words, the first n umericalreceiver makes connection directly for nine subscribers wires and theseconnections are in turn connected to one of a series of secondarynumerical receivers, each of which has provision for connections to oneof a series of numerical receivers of the third order,- the number ofpossible connections therefore being in geometrical progression and thecircuit connections through the primary numerical receiver being adaptedto connect up the individual subscribers connections through theadditional numerical receivers in any desired order.

Fig. 14 of the drawings shows a system approximating a thousandsubscribers lines with circuit connections at the central or switchingstation through the isolator, the general circuit breaker, and threeseries of numerical receivers. The apparatus for operating the isolator,the general circuit breaker, and the numerical receivers is not shown inthis figure of the drawings, nor are all of the one thousand subscriberslines shown, the

diagram being in the nature of a skeleton which illustrates only asufficient number of such lines to give a correct understanding of theswitching circuits through the exchange.

It will be understood that all the subscribers lines come into theoffice at the top of the drawings and divide each into two branches, oneof which is connected to the isolator and the other to the generalcircuit breaker in the manner already described and that all of theselines are broken at the isolator when the preliminary signal is sent inexcept that line over which the impulse is transmitted, and also thatthe other branches are simulta neously broken at the general circuitbreaker until the proper connections are automatically made through thevarious series of numerical receivers and circuit connections, afterwhich it (the general circuit breaker) is restored to its normalposition, the isolator remaining in its abnormal position until theconversation is through, so that all of the subscribers lines are:disconnected at the isolator during the conversation except that of thesubscriber who signaled and that it is automatically released by the actof ringing off, after which any other subscriber may in like mannerobtain control of the isolator and

